The invention relates to an impact wood-splitting tool and, more particularly, to an improved impact tool that has a wood penetrating wedge featuring a reduced recoil surface.
The present invention is related to the impact wood-splitting tool described and illustrated in the aforementioned patent. The impact tool of the patent comprises a shaft having a handle on a proximal end and a wood-splitting wedge on its distal end. The wedge of the tool is positioned upon a piece of wood that is to be split. A weighted hammer surrounds the shaft, and is movably disposed thereupon. The user of the tool uses one hand to slide the hammer downwardly into contact with the wedge, while using the other hand to hold the handle portion in order to keep the shaft upright. The top portion of the wedge is hollow, so that the shaft extends into the wedge and rests upon a blind abutment. A coiled spring surrounds the section of the shaft disposed in the hollow portion of the wedge. The spring is secured within this hollow portion by means of a retaining ring disposed at the top of the hollow section.
The wood is caused to split after one or more thrusts of the weighted hammer against the wedge. The coiled spring operates as an energy transfer mechanism and reduces the recoil of the weighted hammer as it strikes the wedge. The biased hammer strike allows more of the kinetic energy of the hammer to flow into the wedge. As a result of the improved energy transfer, the wedge splits the wood in fewer thrusts of the hammer. Moreover, since the coiled spring effectively disconnects the shaft from the struck wedge, the longevity of the tool itself is enhanced.
Over the years, it has become apparent that there is occasion for certain conditions within a log, such as elasticity and lubricity, to cause the wedge to withdraw from the log after each impact of the hammer. This withdrawal, sometimes referred to as xe2x80x9cbouncexe2x80x9d, can impede the splitting process. One possible way to prevent the wedge from bouncing out of the log is to incorporate a damping unit as part of the hammer in the form of chambers filled with loose lead shot and oil, also referred to as a xe2x80x9cdead blowxe2x80x9d system. This, however, would increase the cost of the tool appreciably.
The present invention reflects the discovery that one can inexpensively eliminate bounce by manipulating the friction of the wedge. The wedge can be fashioned with a frictional duality. It can be made to more easily penetrate past the wood on its downward movement, but have appreciable friction moving upwardly against the wood in recoil, thus eliminating bounce.
The current invention includes a new wedge whose surface may be coated with a friction-reducing coating, such as PTFE (poly-tetra-fluoro-ethylene) or Teflon(copyright), in order to improve its movement past the wood surface during penetration. The surface of the wedge is structurally decreased in recoil by interrupting the metal surface with a plurality of small, periodic, directional or stepped abutments. The abutments catch or snag the surface of the wood when the wedge is caused to move upwardly, similar to the barb of a fishing-hook, which snags the fish after it penetrates its tissue.
In another embodiment of the invention, the wedge can be fabricated from aluminum, whose soft cutting surface can be anodize hardened to prevent deformation. Aluminum is an ideal material for a splitting wedge because of its low mass, which improves transfer of the impact energy of the hammer to wood. The improved energy transfer increases splitting by at least a third. Anodizing also provides an extremely smooth wedge surface that improves penetration into the wood.
U.S. Pat. No. 4,194,544, issued to Scott et al. on Mar. 25, 1980 for SPLITTING DEVICE, describes an elongated cone or splitting wedge having a pointed end and a relatively large blunt end with the intermediate portion flaring outwardly from the pointed end to the blunt end. Serrations are formed in the member adjacent the pointed end. The device is gripped by the user, who thrusts it into a log and then strikes the device with a separate driving maul.
In accordance with the present invention, a wood-splitting impact tool enhances the wood-splitting function by virtue of its improved penetration and its reduced recoil. Improving the penetration of the wedge is achieved by fabricating the wedge of aluminum. Aluminum has rare energy transfer capability, as evidenced by the ball driving capability of aluminum baseball bats. Penetration into wood is also enhanced by using a frictionless or smooth surface coating on the penetrating surfaces of the wedge, such as PTFE, Teflon(copyright), or anodizing the aluminum. Aluminum being softer than steel, its sharp edge and point of impact tend to deform more easily over time. Cutting edge surfaces and can be anodized or xe2x80x9chard coatedxe2x80x9d to toughen as well as smooth these surfaces.
The surface of the wedge is structurally decreased in recoil by interrupting the metal surface with a plurality of small, periodic, barbed or stepped abutments. The abutments catch and/or snag the surface of the wood when the wedge is caused to move upwardly, similar to the barb of a fishing-hook, which snags the fish after it penetrates its tissue.
It is an object of this invention to provide an improved wood-splitting impact tool.
It is another object of the present invention to provide an impact tool for splitting wood, which has a unique duality: improved penetration and decreased recoil.